Neptunians are a humanoid species from the planet Neptune. Neptunians have pig-like noses, purple skin and four arms. Their hair is usually black, but can also be brown ("Spanish Fry"), violet ("Teenage Mutant Leela's Hurdles") and dark blue ("Bender Gets Made"). Because of their many arms, they are usually masters of coordination and can use all four arms simultaniously, giving them an edge in terms of multi-tasking and dexterity. The Neptunians make up a fair share of Earth's alien population and have their own quarter in New New York, Little Neptune, with its own foodshops and other stores. Neptunian cooking is quite famous, and is furtherly promoted by the most prominent member of the Neptunian people, Elzar.

An unknown number of Neptunians are in the service of Robot Santa Claus, but they are constantly mistreated by him so they are forced to take desperate measures in order to survive. Because Santa doesn't feed them, these Neptunians are a lot smaller than their compatriots on Earth, rendering them of similar proportions to the mythical elves who serve the less homicidal, more traditional Santa.